No little green men, no Decepticons, and no risk of imminent invasion characterised a much-hyped NASA announcement on the opening day of the Fall Meeting of the American Geophysical Union (AGU) in San Francisco. Despite popular belief since mid-November that a major and Earth-shaking announcement would be made, the reality has actually offered a tantalising taste of the Curiosity rover’s future promise and a full-up demonstration of its remarkable capabilities. In a sense, the excitement about the discovery of life on Mars has been proven partially true; for Curiosity is so far advanced above and beyond our previous emissaries to the Red Planet that it almost seems that a sentient being is currently trundling its way across Gale Crater. Like a celebrity, it even has more than 1.2 million Twitter followers and has received votes for Time’s Person of the Year. If there is life on Mars, then surely Curiosity is it.
Yesterday’s announcement has shown the world the extent of what the $2.5 billion, six-wheeled rover can do. In early August, it touched down, by means of the revolutionary “Sky Crane,” next to the 18,000-foot peak of Aeolis Mons (“Mount Sharp”) in the 96-mile-wide Gale Crater. For the past 120 days, Curiosity has traversed the Martian surface from its touchdown point at Bradbury Landing—named in honor of sci-fi author Ray Bradbury, who died earlier this year—and has begun to wring out its array of scientific instruments. This array has found what NASA describes as “a complex chemistry within the Martian soil,” including water, sulphur, and chlorine-containing substances.
Soil samples were gathered from the “Rocknest,” a drift of windblown sand and dust, lying slightly downslope from a cluster of dark rocks, as described in this recent AmericaSpace article. Curiosity encountered the drift on Sept. 28, while heading in an east-southeasterly direction toward Glenelg, a geologically significant area, marked by the intersection of three quite distinct terrain types. Measuring about 5 feet by 16 feet in size, the Rocknest provided the setting for Curiosity to perform X-ray diffraction analysis of its first soil specimen.
The rover’s Sample Analysis at Mars (SAM) tool identified oxygen and the chlorine compound perchlorate, which is a particularly reactive chemical already found in northern Martian latitudes by the Phoenix lander. Meanwhile, the Chemistry and Mineralogy (CheMin) instrument processed the soil through a sieve to exclude particles larger than about 0.006 inches across—about the thickness of a human hair—and identified feldspar, pyroxenes, and olivine. A central tenet of the Curiosity mission is to assess past and present environmental conditions on Mars and address the fundamental question of whether Gale Crater ever supported suitable conditions for microbial life.
“We have no definitive detection of Martian organics at this point,” SAM Principal Investigator Paul Mahaffy of NASA’s Goddard Space Flight Center in Greenbelt, Md., admitted during today’s press conference, “but we will keep looking in the diverse environment of Gale Crater.” In addition to the SAM and CheMin results, Curiosity’s robot-arm-mounted Mars Hand Lens Imager (MAHLI) camera drew parallels between the Rocknest and sites previously explored by the Pathfinder, Spirit, and Opportunity rovers in terms of elemental make-up and textual appearance.
Overall, the examination of the Rocknest samples discovered that their composition is approximately one-half “common” volcanic materials and about one-half “non-crystalline” materials, such as glass. Information was returned about ingredients present in smaller concentrations and isotopic ratios as well. It was strongly stressed that the presence of water molecules in no way implies that the Rocknest drift was, at any time, “wet.” “Water molecules bound to grains of sand or dust are not unusual,” noted NASA’s official announcement, “but the quantity seen was higher than anticipated.”
John Grotzinger, Curiosity’s Project Scientist, was the source of the rampant internet speculation since mid-November, when he made reference to the collection of data “for the history books.” This was misinterpreted by many as an indication that a discovery of Earth-shattering importance had been made. The reality is that today’s news is indeed one for the history books, for never before has a scientific payload with Curiosity’s degree of sophistication been brought to bear on a Martian soil sample. “The synergies of the instruments and richness of the data sets,” said Grotzinger, “give us great promise for using them at the mission’s main science destination on Mount Sharp.”